CVE-2026-98325
Summary
by MITRE • 10/06/2026
In the Linux kernel, the following vulnerability has been resolved:
wifi: mac80211: set up the TX info early to fix failure paths
The previous commit 2c51457d930f ("wifi: mac80211: free ack status frame on TX header build failure") cleaned up the leak, but still left the code a bit messy and the failed SKB didn't get reported to userspace.
Fix this up by initialising skb->cb[] earlier, which allows using
ieee80211_free_txskb() and therefore reports it for the failure in ieee80211_build_hdr(), and unifies the ieee80211_skb_resize() failure path with it.
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Analysis
by VulDB Data Team • 10/06/2026
The vulnerability addressed involves a flaw within the Linux kernel's mac80211 wireless subsystem, specifically concerning the handling of transmission control blocks during packet construction failures. The core issue stems from the late initialization of the socket buffer callback array, known as skb->cb[]. In network stack operations, this data structure is critical for passing metadata and status information between different layers of the networking code. When a failure occurs during the building of an 80211 header via ieee80211_build_hdr(), or when resizing the socket buffer fails, the lack of early initialization prevents the proper invocation of cleanup routines such as ieee80211_free_txskb(). This results in two distinct operational defects: a potential resource leak and a failure to report transmission status back to user-space applications.
From a technical perspective, this flaw represents an improper initialization of resources before error handling paths are executed. The previous mitigation attempt focused solely on freeing the acknowledgment status frame but neglected to ensure that the socket buffer's control block was populated with necessary context data required by the free routine. Consequently, when ieee80211_build_hdr() encounters an error condition, such as insufficient memory or invalid parameters, the code path intended to clean up and report this failure is bypassed or executed incorrectly because the requisite metadata in skb->cb[] remains uninitialized. This leads to a situation where the kernel fails to properly release associated resources or notify higher-level protocols about the transmission failure, potentially causing state inconsistencies within the wireless driver stack.
The operational impact of this vulnerability includes potential memory leaks and degraded reliability for network applications relying on accurate feedback regarding packet transmission status. While immediate denial-of-service is not explicitly described as a direct consequence in the patch notes, resource exhaustion over time due to unreported failures could degrade system performance. Furthermore, user-space daemons that monitor wireless link quality or manage connection states may receive incomplete or missing error reports, leading to incorrect decision-making regarding network reconfiguration or fallback mechanisms. This affects the robustness of the wireless networking stack under high-load conditions or when dealing with malformed packets that trigger header build failures frequently.
This issue aligns with CWE-457, which describes an Uninitialized Variable Usage vulnerability. The failure to initialize skb->cb[] before accessing it in error paths constitutes a classic instance of using uninitialized data structures for control flow decisions and resource management. Additionally, the lack of proper reporting to user-space can be associated with CWE-209, where information about errors is not properly exposed, hindering effective monitoring and debugging efforts by system administrators or security tools. The ATT&CK framework does not directly map this specific kernel bug to a tactical technique as it is an internal stability issue rather than an exploit vector for external attackers, but it relates broadly to the concept of resource exhaustion if left unpatched in high-volume environments.
Mitigation strategies primarily involve applying the upstream Linux kernel patch that restructures the initialization order within mac80211. System administrators should ensure their systems are updated with the latest stable kernel versions containing this fix. For organizations unable to immediately update, monitoring logs for wireless driver errors and unusual memory usage patterns can help detect potential resource leaks associated with this flaw. Long-term remediation requires rigorous code review practices that mandate early initialization of all data structures required by error handling paths, ensuring that cleanup routines like ieee80211_free_txskb() are always safe to call regardless of where a failure occurs during packet processing.